CS Homework 10

Transcription

1 CS Homework 10 p. 1 Deadline: CS Homework 10 Problem 1 -- answering reading questions on Canvas for DB Reading Packet 9 -- must be completed by 10:45 am on Tuesday, November 14. Problem 2 -- answering reading questions on Canvas for DB Reading Packet must be completed by 10:45 am on Thursday, November 16. The remaining problems are due by 11:59 pm on Friday, November 17, Purpose: To get experience converting an ER model involving supertype/subtype entity classes into a (partial) database design/schema, to think some more about integrities supported by DBMSs, to think about desired properties of database transactions, to practice writing more queries, including queries involving joins of more than two tables, and to practice with a view and a sequence. How to submit Problems 1 and 2 will be completed on the course Canvas site. For Problem 3 onward: Each time you wish to submit, within the directory 325hw10 on nrs-projects.humboldt.edu (and at the nrsprojects UNIX prompt, NOT inside sqlplus!) type: ~st10/325submit...to submit your current files, using a homework number of 10. (Make sure that the files you intend to submit are listed as having been submitted!) Additional notes: DB Reading Packets 7, 8, and 9 and SQL Reading Packets 6 and 7, on the course Canvas site, along with the posted in-class projections from the public course web site, are useful references for this homework. Now that we have covered the order by clause, you are expected to use it appropriately when an explicit row ordering is specified. Queries for problems asking for explicit row ordering will be incorrect if they do not include a reasonable order by clause. You are required to use the HSU Oracle student database for Problem 5. You are expected to follow course style standards for SQL and SQL*Plus statements as noted in previous homework handouts and as mentioned in class. An example hw10-out.txt has been posted along with this homework handout, to help you see if you are on the right track with your queries for Problem 5. If your hw10-out.txt matches this posted one, that doesn't guarantee that you wrote appropriate queries, but it is an encouraging sign.

2 CS Homework 10 p. 2 (I added a few extra prompt commands near the beginning of this script to output some blank lines for slightly-prettier output.) Problem 1 Correctly complete the Reading Questions for DB Reading Packet 9, on the course Canvas site, by 10:45 am on Tuesday, November 14. Problem 2 Correctly complete the Reading Questions for DB Reading Packet 10, on the course Canvas site, by 10:45 am on Thursday, November 16. Problem 3 Use ssh to connect to nrs-projects.humboldt.edu, and create a directory named 325hw10 on nrsprojects: mkdir 325hw10...and change this directory's permissions so that only you can read it: chmod hw10...and change your current directory to that directory (go to that new directory) to do this problem: cd 325hw10 Put all of your files for this homework in this directory. (And it is from this directory that you should type ~st10/325submit to submit your files each time you want to submit the work you have done so far.) Place your answers for this problem into file hw10-3.txt For this problem, you will be converting two database models into a (partial) database design/schema. (Why partial? Because, for this assignment, we are not including domains or business rules, which are part of a database design/schema, also.) Consider the following ER models. Convert each into an appropriate corresponding (partial) design/schema, using the conversion rules discussed in lecture. Your resulting database designs/schemas needs to meet the following requirements: list your resulting tables in relation structure form, indicating foreign keys by writing SQL foreign key clauses after the relation structure. make sure, for each table, that you clearly indicate primary key attributes by writing them in all-uppercase (and by writing non-primary-key attributes NOT in all-uppercase). do not make ANY inferences/assumptions NOT supported by the given models or stated along with them. (Assume that the models DO reflect the scenarios faithfully.)

3 CS Homework 10 p. 3 3 part a's model: 3 part b's model: Donation N donated-by 1 Booster Student N has-guardian M o Parent Alum Friend Donation Booster Student Parent Alum Friend DON_NUM BOOSTER_NUM STU_ID Vol_hrs Year_left Year_joined Don_date Booster_lname Stu_lname Prefd_phone Don_amount Booster_fname Booster_ Stu_fname Stu_grade Stu_gpa

4 CS Homework 10 p. 4 Problem 4 Place your name and then your answers for this part in a file named hw10-4.txt within your 325hw10 directory. for problems 4-1 through 4-8: We have discussed entity integrity, domain integrity, referential integrity, and transaction integrity, and how a DBMS may support (or enforce) them. Give the most appropriate of these four types of integrity in answer to each of the following: problem 4-1 This is being supported (to at least some degree) in the Oracle DBMS by refusal to allow the insertion of an attribute value that is not the given type for that attribute (based on the type declaration for that attribute). (that is, this kind of integrity is being enforced when the Oracle DBMS will not permit the insertion of a row that includes a date value for a column declared to be of type integer) problem 4-2 This is being supported when a DBMS does not permit the insertion of a row with the same primary key as an already-existing row in that table. problem 4-3 This is being supported when a DBMS does not permit the insertion of a row with a foreign key value for which there is not a corresponding primary key value in the parent table. problem 4-4 Oracle SQL supports this with its COMMIT and ROLLBACK statements. problem 4-5 If a DBMS permitted you to insert duplicate rows within a table, it would not be supporting this. problem 4-6 One way in which Oracle DBMS supports this is with its "on delete restrict" default for foreign keys --- that is, in Oracle, if you attempt to delete a parent row with a primary key matching children rows with that value for their foreign key, you are not permitted to do so. problem 4-7 When a DBMS has automatic backup and recovery capabilities, it could be said to be providing support for this (in terms of the desired property of durability). problem 4-8 Oracle is providing additional support for this with the check clauses that one may use in a create table statement to restrict the allowed values in a particular column, which it then uses to only permit insertions of rows which have values for that column that satisfy the check clause.

5 CS Homework 10 p. 5 for problems 4-9 through 4-14: We have discussed five desired properties for database transactions: atomicity, consistency, isolation, durability, serializability (ACIDS) Give the most appropriate of these five desired properties in answer to each of the following: problem 4-9 Which of these is particularly about the database maintaining its consistent state between transactions? problem 4-10 Which of these do you have when the concurrent execution of transactions is equivalent to the case where the transactions executed serially in some arbitrary order? problem 4-11 Which of these stipulates that a transaction has to transform a database from one consistent state to another consistent state? problem 4-12 Which two of these is it the responsibility of the recovery subsystem to ensure? problem 4-13 Which of these means that the data used during the execution of a transaction cannot be used by a second transaction until the first one is completed (at least, the effect must be as if this was the case)? problem 4-14 Which of these is the "all or nothing" property, requiring either that all operations/parts/steps of a transaction be completed in their entirety, or not performed at all? Problem 5 This problem again uses the tables created by the SQL script movies-create.sql and populated by movies-pop.sql. As a reminder, these tables can be described in relation structure form as: Movie_category(CATEGORY_CODE, category_name) Client(CLIENT_NUM, client_lname, client_fname, client_phone, client_credit_rtg, client_fave_cat) foreign key (client_fave_cat) references movie_category(category_code) Movie(MOVIE_NUM, movie_title, movie_director_lname, movie_yr_released, movie_rating, category_code) foreign key(category_code) references movie_category Video(VID_ID, vid_format, vid_purchase_date, vid_rental_price, movie_num) foreign key (movie_num) references movie Rental(RENTAL_NUM, client_num, vid_id, date_out, date_due, date_returned) foreign key (client_num) references client, foreign key(vid_id) references video And, again, for your convenience as a reference, a handout of these relation structures is posted along with this homework handout.

6 CS Homework 10 p. 6 These tables should still exist in your database from Homework 5, so you should not need to re-run movies-create.sql. Because we modified these tables' contents in Homework 9, for Homework 10 you should restore them to those populated by movies-pop.sql: Make a copy of movies-pop.sql in your 325hw10 directory -- one way to do so is using: cp ~st10/movies-pop.sql. (REMEMBER the space and the. at the end!) Now enter sqlplus and run your movies-pop.sql copy. With these tables now populated as we'd like, now create a file named hw10.sql and include the following within one or more SQL comments: your name CS Homework 10 - Problem 5 the date this file was last modified Then: use spool to start writing the results for this script's actions into a file hw10-out.txt put in a prompt command printing Homework 10 Problem 5 put in a prompt command printing your name include a spool off command, at the BOTTOM/END of this file. Type your answers to the problems below BEFORE this spool off command! Now, within your file hw10.sql, add in SQL statements for the following, PRECEDING EACH with a SQL*Plus prompt command noting what problem part it is for. Problem 5-1 Posted along with this homework handout is a "Note on Joining More than 2 Tables". You need some practice with this, so read over this handout, and then write the following query. Write a query that will project, for each rental, the renting client's last name, and the rented video's format, displaying the results in order of client's last name, and in secondary order by rented video's format. Problem 5-2 Write a query that will project, for each rental, the rented video's movie's title, the rented video's format, and the data that that rental is due to be returned, displaying the results in order of movie title, and in secondary order in descending order of date due (that is, latest date due first). Problem 5-3 Write a query that will project, for each rental, the renting client's last name, and the rented video's movie's title, displaying the results in order of client's last name, and in secondary order by movie title. Problem 5-4 Write a query that will project, JUST for not-yet-returned rentals, the renting client's last name, the rented video's movie's title, and the date due for that rental, displaying the results in order of rental date due, and in secondary order by client last name.

7 CS Homework 10 p. 7 Problem 5-5 Write a query that will project the client last name and the number of rentals made by that client, but only for clients who have rented at least one video, displaying the results in descending order of number of rentals, and in secondary order by client last name. Problem 5-6 Write a query which will project the average rental price and number of such videos for videos of Classic movies -- BUT! You must write this without explicitly using the category code for Classic movies; you must use the name 'Classic' in your query instead. Rename the columns to be "Avg Cost - Classic" and "# Videos - Classic", respectively, using precisely these spaces and case. HINT: be careful -- what tables actually need to be involved here? look carefully at the foreign keys of tables involved to determine what those join conditions should be, looking for columns with common domains where their being equal in the Cartesian product has useful meaning Problem 5-7 For each movie category, now project the movie category name, and the number of videos of movies in that category using the column alias "# VIDS". (Be sure you are clear: in this problem, you are projecting the number of videos of movies in each category.) Display the resulting rows in reverse order of the number of videos in each category(that is, display the row with the category with the most videos first). Problem 5-8 Consider your query from Problem 5-7. You decide that you are really only interested in the movie categories for which there are fewer than 7 videos in that category. For this problem, project the movie category name and the number of videos of movies in that category only for movie categories with fewer than 7 videos, again using the column alias "# VIDS". Display the resulting rows in reverse order of the number of videos in each category(from highest to lowest). Problem 5-9 Drop and create a view called movie_list of the movie and movie_category tables, containing only the category name, movie rating, and movie title for each movie. Follow that with a query showing all of the contents of this view, displaying the rows in order of movie rating, with a secondary ordering by movie title. Problem 5-10 Drop and create a new table (not already used in movies-create.sql nor in lab) that has at least three columns. Then, drop and create a sequence suitable for use in setting the primary key of this new table. Have your sequence start at a value other than 1. Problem 5-11 Insert at least 3 rows into your table from Problem 5-10, using your sequence from Problem 5-10 to set each new row's primary key. Then, write a query showing the contents of this table.

8 CS Homework 10 p. 8 When you think the results of all of these queries look correct, this would also be a good time to look at the contents of hw10-out.txt -- at the nrs-projects prompt (the UNIX level, NOT in sqlplus!), type: more hw10-out.txt You should see that hw10-out.txt contains the query results you just saw within sqlplus. (And, remember that you can compare your hw10-out.txt contents to those in the posted example hw10-out.txt posted along with this homework handout, to help you see if you are on the right track with your answers, although remember to also meet each problem's stated requirements and the class style standards.) When you are satisfied with these, then hw10.sql and hw10-out.txt are completed.